Application of a New Mathematical Model for Fluid-Rock Interaction to Contact and Regional Metamorphism

提出了一种新的流-岩相互作用数学模型，克服了计算流-岩比时存在的假设问题。新模型可以根据岩石样品的岩石学、地球化学和/或同位素数据确定时间积分通量（每面积岩石的体积流体单位）和流动方向。如果可以估计流动持续时间和流体压力梯度，则可以计算达西速度和原位渗透率。本研究将进一步发展该模型，并将其应用于接触变质作用和区域变质作用的若干重大问题。结果将首次系统地确定大范围变质环境中的通量、流动方向和岩石渗透率。具体项目包括：(1)在整个区域变质地体（佛蒙特州东部的Waits河组）范围内流体流动的数量、几何形状和地质控制；(b)韧性剪切带中流体流动的数量和方向及其与交代作用的关系（苏格兰西北部Scourie剪切带）；(c)一个主要花岗岩基（内华达山脉的顶板垂饰）顶部流体流动的数量、地质控制和化学效应；(d)流体流动在厌氧症中的作用（缅因州中部奥纳瓦接触光圈）；(e)极低等级区域变质作用（瑞士阿尔卑斯山脉中部的叠世黑色页岩）期间流体流动的数量和岩石学效应；(f)流体流动在区域交代作用中的作用（缅因州中南部Vassalboro组）。

A new mathematical model for fluid-rock interaction has been developed that overcomes the problematic assumptions in calculations of fluid-rock ratios. The new model permits determination of time-integrated fluxes (units of volume fluid per area rock) and direction of flow from petrologic, geochemical, and/or isotopic data on rock samples. If duration of flow and fluid pressure gradients can be estimated, Darcy velocities, and in situ permeabilities may be computed. Proposed research will further develop the model and apply it to several significant problems in contact and regional metamorphism. Results will provide the first systematic determination of fluxes, flow directions, and rock permeabilities in a wide range of metamorphic environments. Specific projects include: (1) the amount, geometry, and geologic controls of fluid flow on the scale of an entire regional metamorphic terrane (Waits River Formation, eastern Vermont); (b) the amounts and direction of fluid flow in a ductile shear zone and their relation to metasomatism (shear zones at Scourie, northwest Scotland); (c) the amount, geologic controls, and chemical effects of fluid flow at the top of a major granitic batholith (roof pendants in the Sierra Nevada); (d) the role of fluid flow in anatexis (Onawa contact aureole, central Maine); (e) the amount and petrologic effect of fluid flow during very low-grade regional metamorphism (Liassic black shales, central Swiss Alps); and (f) the role of fluid flow in regional metasomatism (Vassalboro Formation, south-central Maine).